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Ono M, Izumi Y, Maruyama K, Yasuoka Y, Hiramatsu A, Aramburu J, López-Rodríguez C, Nonoguchi H, Kakizoe Y, Adachi M, Kuwabara T, Mukoyama M. Characterization of gene expression in the kidney of renal tubular cell-specific NFAT5 knockout mice. Am J Physiol Renal Physiol 2024; 326:F394-F410. [PMID: 38153851 DOI: 10.1152/ajprenal.00233.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 12/18/2023] [Accepted: 12/18/2023] [Indexed: 12/30/2023] Open
Abstract
Nuclear factor of activated T cells 5 (NFAT5; also called TonEBP/OREBP) is a transcription factor that is activated by hypertonicity and induces osmoprotective genes to protect cells against hypertonic conditions. In the kidney, renal tubular NFAT5 is known to be involved in the urine concentration mechanism. Previous studies have suggested that NFAT5 modulates the immune system and exerts various effects on organ damage, depending on organ and disease states. Pathophysiological roles of NFAT5 in renal tubular cells, however, still remain obscure. We conducted comprehensive analysis by performing transcription start site (TSS) sequencing on the kidney of inducible and renal tubular cell-specific NFAT5 knockout (KO) mice. Mice were subjected to unilateral ureteral obstruction to examine the relevance of renal tubular NFAT5 in renal fibrosis. TSS sequencing analysis identified 722 downregulated TSSs and 1,360 upregulated TSSs, which were differentially regulated ≤-1.0 and ≥1.0 in log2 fold, respectively. Those TSSs were annotated to 532 downregulated genes and 944 upregulated genes, respectively. Motif analysis showed that sequences that possibly bind to NFAT5 were enriched in TSSs of downregulated genes. Gene Ontology analysis with the upregulated genes suggested disorder of innate and adaptive immune systems in the kidney. Unilateral ureteral obstruction significantly exacerbated renal fibrosis in the renal medulla in KO mice compared with wild-type mice, accompanied by enhanced activation of immune responses. In conclusion, NFAT5 in renal tubules could have pathophysiological roles in renal fibrosis through modulating innate and adaptive immune systems in the kidney.NEW & NOTEWORTHY TSS-Seq analysis of the kidney from renal tubular cell-specific NFAT5 KO mice uncovered novel genes that are possibly regulated by NFAT5 in the kidney under physiological conditions. The study further implied disorders of innate and adaptive immune systems in NFAT5 KO mice, thereby exacerbating renal fibrosis at pathological states. Our results may implicate the involvement of renal tubular NFAT5 in the progression of renal fibrosis. Further studies would be worthwhile for the development of novel therapy to treat chronic kidney disease.
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Affiliation(s)
- Makoto Ono
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
| | - Yuichiro Izumi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
| | - Kosuke Maruyama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
| | - Yukiko Yasuoka
- Department of Physiology, Kitasato University School of Medicine, Sagamihara, Japan
| | - Akiko Hiramatsu
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
| | - Jose Aramburu
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra and Barcelona Biomedical Research Park, Barcelona, Spain
| | - Cristina López-Rodríguez
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra and Barcelona Biomedical Research Park, Barcelona, Spain
| | - Hiroshi Nonoguchi
- Division of Internal Medicine, Kitasato University Medical Center, Saitama, Japan
| | - Yutaka Kakizoe
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
| | - Masataka Adachi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
| | - Takashige Kuwabara
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
| | - Masashi Mukoyama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
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2
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Pap D, Pajtók C, Veres-Székely A, Szebeni B, Szász C, Bokrossy P, Zrufkó R, Vannay Á, Tulassay T, Szabó AJ. High Salt Promotes Inflammatory and Fibrotic Response in Peritoneal Cells. Int J Mol Sci 2023; 24:13765. [PMID: 37762068 PMCID: PMC10531298 DOI: 10.3390/ijms241813765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 09/01/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Recent studies draw attention to how excessive salt (NaCl) intake induces fibrotic alterations in the peritoneum through sodium accumulation and osmotic events. The aim of our study was to better understand the underlying mechanisms. The effects of additional NaCl were investigated on human primary mesothelial cells (HPMC), human primary peritoneal fibroblasts (HPF), endothelial cells (HUVEC), immune cells (PBMC), as well as ex vivo on peritoneal tissue samples. Our results showed that a high-salt environment and the consequently increased osmolarity increase the production of inflammatory cytokines, profibrotic growth factors, and components of the renin-angiotensin-aldosterone system, including IL1B, IL6, MCP1, TGFB1, PDGFB, CTGF, Renin and Ace both in vitro and ex vivo. We also demonstrated that high salt induces mesenchymal transition by decreasing the expression of epithelial marker CDH1 and increasing the expression of mesenchymal marker ACTA2 and SNAIL1 in HPMCs, HUVECs and peritoneal samples. Furthermore, high salt increased extracellular matrix production in HPFs. We demonstrated that excess Na+ and the consequently increased osmolarity induce a comprehensive profibrotic response in the peritoneal cells, thereby facilitating the development of peritoneal fibrosis.
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Affiliation(s)
- Domonkos Pap
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
- HUN-REN–SU Pediatrics and Nephrology Research Group, 1052 Budapest, Hungary
| | - Csenge Pajtók
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
| | - Apor Veres-Székely
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
- HUN-REN–SU Pediatrics and Nephrology Research Group, 1052 Budapest, Hungary
| | - Beáta Szebeni
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
- HUN-REN–SU Pediatrics and Nephrology Research Group, 1052 Budapest, Hungary
| | - Csenge Szász
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
| | - Péter Bokrossy
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
| | - Réka Zrufkó
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
| | - Ádám Vannay
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
- HUN-REN–SU Pediatrics and Nephrology Research Group, 1052 Budapest, Hungary
| | - Tivadar Tulassay
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
- HUN-REN–SU Pediatrics and Nephrology Research Group, 1052 Budapest, Hungary
| | - Attila J. Szabó
- Pediatric Center, MTA Center of Excellence, Semmelweis University, 1085 Budapest, Hungary
- HUN-REN–SU Pediatrics and Nephrology Research Group, 1052 Budapest, Hungary
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3
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Hiramatsu A, Izumi Y, Eguchi K, Matsuo N, Deng Q, Inoue H, Nakayama Y, Nonoguchi H, Aramburu J, López-Rodríguez C, Kakizoe Y, Adachi M, Kuwabara T, Kim-Mitsuyama S, Mukoyama M. Salt-Sensitive Hypertension of the Renal Tubular Cell-Specific NFAT5 (Nuclear Factor of Activated T-Cells 5) Knockout Mice. Hypertension 2021; 78:1335-1346. [PMID: 34601973 DOI: 10.1161/hypertensionaha.121.17435] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Akiko Hiramatsu
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Yuichiro Izumi
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Koji Eguchi
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Naomi Matsuo
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Qinyuan Deng
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Hideki Inoue
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Yushi Nakayama
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Hiroshi Nonoguchi
- Division of Internal Medicine, Kitasato University Medical Center, Kitamoto, Saitama, Japan (H.N.)
| | - Jose Aramburu
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, and Barcelona Biomedical Research Park, Spain (J.A., C.L.-R.)
| | - Cristina López-Rodríguez
- Immunology Unit, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, and Barcelona Biomedical Research Park, Spain (J.A., C.L.-R.)
| | - Yutaka Kakizoe
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Masataka Adachi
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Takashige Kuwabara
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Shokei Kim-Mitsuyama
- Department of Pharmacology and Molecular Therapeutics (S.K.-M.), Kumamoto University Graduate School of Medical Sciences, Japan
| | - Masashi Mukoyama
- Department of Nephrology (A.H., Y.I., K.E., N.M., Q.D., H.I., Y.N., Y.K., M.A., T.K., M.M.), Kumamoto University Graduate School of Medical Sciences, Japan
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4
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Baliou S, Kyriakopoulos AM, Goulielmaki M, Panayiotidis MI, Spandidos DA, Zoumpourlis V. Significance of taurine transporter (TauT) in homeostasis and its layers of regulation (Review). Mol Med Rep 2020; 22:2163-2173. [PMID: 32705197 PMCID: PMC7411481 DOI: 10.3892/mmr.2020.11321] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/09/2020] [Indexed: 11/05/2022] Open
Abstract
Taurine (2‑aminoethanesulfonic acid) contributes to homeostasis, mainly through its antioxidant and osmoregulatory properties. Taurine's influx and efflux are mainly mediated through the ubiquitous expression of the sodium/chloride‑dependent taurine transporter, located on the plasma membrane. The significance of the taurine transporter has been shown in various organ malfunctions in taurine‑transporter‑null mice. The taurine transporter differentially responds to various cellular stimuli including ionic environment, electrochemical charge, and pH changes. The renal system has been used as a model to evaluate the factors that significantly determine the regulation of taurine transporter regulation.
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Affiliation(s)
- Stella Baliou
- National Hellenic Research Foundation, 11635 Athens, Greece
| | | | | | - Michalis I Panayiotidis
- Department of Electron Microscopy and Molecular Pathology, The Cyprus Institute of Neurology and Genetics, 2371 Nicosia, Cyprus
| | - Demetrios A Spandidos
- Laboratory of Clinical Virology, Medical School, University of Crete, 71003 Heraklion, Greece
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5
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Pelzl L, Sahu I, Ma K, Heinzmann D, Bhuyan AAM, Al-Maghout T, Sukkar B, Sharma Y, Marini I, Rigoni F, Artunc F, Cao H, Gutti R, Voelkl J, Pieske B, Gawaz M, Bakchoul T, Lang F. Beta-Glycerophosphate-Induced ORAI1 Expression and Store Operated Ca 2+ Entry in Megakaryocytes. Sci Rep 2020; 10:1728. [PMID: 32015442 PMCID: PMC6997179 DOI: 10.1038/s41598-020-58384-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 01/03/2020] [Indexed: 12/13/2022] Open
Abstract
Impairment of renal phosphate elimination in chronic kidney disease (CKD) leads to enhanced plasma and tissue phosphate concentration, which in turn up-regulates transcription factor NFAT5 and serum & glucocorticoid-inducible kinase SGK1. The kinase upregulates ORAI1, a Ca2+-channel accomplishing store-operated Ca2+-entry (SOCE). ORAI1 is stimulated following intracellular store depletion by Ca2+-sensors STIM1 and/or STIM2. In megakaryocytes and blood platelets SOCE and thus ORAI1 are powerful regulators of activity. The present study explored whether the phosphate-donor ß-glycerophosphate augments NFAT5, ORAI1,2,3 and/or STIM1,2 expressions and thus SOCE in megakaryocytes. Human megakaryocytic Meg01cells were exposed to 2 mM of phosphate-donor ß-glycerophosphate for 24 hours. Platelets were isolated from blood samples of patients with impaired kidney function or control volunteers. Transcript levels were estimated utilizing q-RT-PCR, cytosolic Ca2+-concentration ([Ca2+]i) by Fura-2-fluorescence, and SOCE from increase of [Ca2+]i following re-addition of extracellular Ca2+ after store depletion with thapsigargin (1 µM). NFAT5 and ORAI1 protein abundance was estimated with Western blots. As a result, ß-glycerophosphate increased NFAT5, ORAI1/2/3, STIM1/2 transcript levels, as well as SOCE. Transcript levels of NFAT5, SGK1, ORAI1/2/3, and STIM1/2 as well as NFAT5 and ORAI1 protein abundance were significantly higher in platelets isolated from patients with impaired kidney function than in platelets from control volunteers. In conclusion, phosphate-donor ß-glycerophosphate triggers a signaling cascade of NFAT5/SGK1/ORAI/STIM, thus up-regulating store-operated Ca2+-entry.
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Affiliation(s)
- Lisann Pelzl
- Transfusion Medicine, Medical Faculty, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Itishri Sahu
- Department of Internal Medicine III, Eberhard Karl University Tuebingen, Tuebingen, Germany.,Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Ke Ma
- Department of Internal Medicine III, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - David Heinzmann
- Department of Internal Medicine III, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | | | - Tamer Al-Maghout
- Department of Internal Medicine III, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Basma Sukkar
- Department of Internal Medicine III, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Yamini Sharma
- Department of Internal Medicine III, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Irene Marini
- Transfusion Medicine, Medical Faculty, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Flaviana Rigoni
- Transfusion Medicine, Medical Faculty, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Ferruh Artunc
- Department of Internal Medicine IV, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Hang Cao
- Department of Internal Medicine III, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Ravi Gutti
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Jakob Voelkl
- Institute for Physiology, Johannes Kepler University, Linz, Austria.,DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany.,Department of Nephrology and Medical Intensive Care, Charité University Medicine, Berlin, Germany.,Department of Internal Medicine and Cardiology, Campus Virchow Klinikum, Charité University Medicine, Berlin, Germany
| | - Burkert Pieske
- DZHK (German Centre for Cardiovascular Research), partner site Berlin, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, and Department of Internal Medicine and Cardiology, German Heart Center Berlin (DHZB), Berlin, Germany.,Department of Internal Medicine and Cardiology, Campus Virchow Klinikum, Charité University Medicine, Berlin, Germany
| | - Meinrad Gawaz
- Department of Internal Medicine III, Eberhard Karl University Tuebingen, Tuebingen, Germany
| | - Tamam Bakchoul
- Transfusion Medicine, Medical Faculty, Eberhard Karl University Tuebingen, Tuebingen, Germany.,Centre for Clinical Transfusion Medicine, University Hospital of Tuebingen, Tuebingen, Germany
| | - Florian Lang
- Department of Vegetative and Clinical Physiology, Eberhard Karl University Tuebingen, Tuebingen, Germany.
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6
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Albertoni Borghese MF, Hope S, Ortiz MDC, Barchuk M, Kessler C, Davio C, Vatta M, Majowicz M. Altered expression of Aquaporin-2 in one-kidney, one-clip hypertension. Life Sci 2018; 208:72-78. [PMID: 30009821 DOI: 10.1016/j.lfs.2018.07.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 07/04/2018] [Accepted: 07/12/2018] [Indexed: 11/30/2022]
Abstract
AIMS The aim of the present study was to evaluate the regulation of Aquaporin-2 (AQP2) water channel in the kidney of one-kidney, one-clip rats (Goldblatt-1 model). In addition, some mechanisms that underlie the role of AQP2 in the Goldblatt-1 model were evaluated. MAIN METHODS Sprague-Dawley rats were divided in three groups: control two-kidney, no clip (C, 2 K-NC); nephrectomized one-kidney, no clip (N, 1 K-NC) and Goldblatt one-kidney, one-clip (G, 1 K-1C). AQP2 expression (by westernblot, real time PCR, immunohistochemistry and immunofluorescence), vasopressin V2 receptor expression (by real time PCR), cAMP concentration, NFkB and TonEBP (cytosol to nucleus ratio) were evaluated in the renal medulla. KEY FINDINGS AQP2 expression, V2 receptor expression and cAMP concentration were decreased in the renal medulla of 1 K-1C rats, NFkB translocation was favoured towards the nucleus suggesting its activation while TonEBP translocation was not altered in this model of hypertension. SIGNIFICANCE In this model of hypertension the decrease of AQP2 expression could be a mechanism that counteracts the high blood pressure promoting water excretion and this may be consequence of decreased vasopressin sensitivity and/or the increased activity of NFkB at renomedullary collecting duct level. Given that renovascular hypertension is among the most common causes of secondary hypertension, it is important to elucidate all the relevant mechanisms involved in the generation or in the compensation of the hypertensive state in order to improve the diagnoses and treatment of the patients.
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Affiliation(s)
- Maria Florencia Albertoni Borghese
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Buenos Aires, Argentina; Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Buenos Aires, Argentina
| | - Sandra Hope
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Fisiología, Buenos Aires, Argentina; Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Química y Metabolismo del Fármaco (IQUIMEFA), Buenos Aires, Argentina
| | - Maria Del Carmen Ortiz
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Buenos Aires, Argentina
| | - Magalí Barchuk
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Buenos Aires, Argentina
| | - Camila Kessler
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Buenos Aires, Argentina
| | - Carlos Davio
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Farmacología, Buenos Aires, Argentina; Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Marcelo Vatta
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Fisiología, Buenos Aires, Argentina; Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Química y Metabolismo del Fármaco (IQUIMEFA), Buenos Aires, Argentina
| | - Mónica Majowicz
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Biología Celular y Molecular, Buenos Aires, Argentina.
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7
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Sahu I, Pelzl L, Sukkar B, Fakhri H, al‐Maghout T, Cao H, Hauser S, Gutti R, Gawaz M, Lang F. NFAT5‐sensitive Orai1 expression and store‐operated Ca
2+
entry in megakaryocytes. FASEB J 2017; 31:3439-3448. [DOI: 10.1096/fj.201601211r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Itishri Sahu
- Department of Cardiology and Vascular Medicine and PhysiologyUniversity of Tübingen Tübingena Germany
- Department of BiochemistrySchool of Life SciencesUniversity of Hyderabad Hyderabad India
| | - Lisann Pelzl
- Department of Cardiology and Vascular Medicine and PhysiologyUniversity of Tübingen Tübingena Germany
| | - Basma Sukkar
- Department of Cardiology and Vascular Medicine and PhysiologyUniversity of Tübingen Tübingena Germany
| | - Hajar Fakhri
- Department of Cardiology and Vascular Medicine and PhysiologyUniversity of Tübingen Tübingena Germany
| | - Tamer al‐Maghout
- Department of Cardiology and Vascular Medicine and PhysiologyUniversity of Tübingen Tübingena Germany
| | - Hang Cao
- Department of Cardiology and Vascular Medicine and PhysiologyUniversity of Tübingen Tübingena Germany
| | - Stefan Hauser
- German Center for Neurodegenerative Diseases Tübingen Germany
| | - Ravi Gutti
- Department of BiochemistrySchool of Life SciencesUniversity of Hyderabad Hyderabad India
| | - Meinrad Gawaz
- Department of Cardiology and Vascular Medicine and PhysiologyUniversity of Tübingen Tübingena Germany
| | - Florian Lang
- Department of Cardiology and Vascular Medicine and PhysiologyUniversity of Tübingen Tübingena Germany
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8
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Chua OWH, Wong KKL, Ko BC, Chung SK, Chow BKC, Lee LTO. Role of nuclear factor of activated T-cells 5 in regulating hypertonic-mediated secretin receptor expression in kidney collecting duct cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:922-32. [PMID: 27080132 DOI: 10.1016/j.bbagrm.2015.12.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 11/27/2015] [Accepted: 12/21/2015] [Indexed: 11/18/2022]
Abstract
A growing body of evidence suggests that secretin (SCT) is an important element in the osmoregulatory pathway. It is interesting to note that both SCT and its receptor (SCTR) gene are activated upon hyperosmolality in the kidney. However, the precise molecular mechanisms underlying the induction of the SCTR gene expression in response to changes in osmolality have yet to be clarified. Detailed DNA sequence analysis of the promoter regions of the SCTR gene reveals the presence of multiple osmotic response elements (ORE). The ORE is the binding site of a key osmosensitive transactivator, namely, the nuclear factor of activated T-cells 5 (NFAT5). SCTR and NFAT5 are co-expressed in the kidney cortex and medulla collecting duct cells. We therefore hypothesize that NFAT5 is responsible for modulating SCTR expression in hypertonic environments. In this study, we found hypertonicity stimulates the promoter activities and endogenous gene expression of SCTR in mouse kidney cortex collecting duct cells (M1) and inner medulla collecting duct cells (mIMCD3). The overexpression and silencing of NFAT5 further confirmed it to be responsible for the up-regulation of the SCTR gene under hypertonic conditions. A significant increase in the interaction between NFAT5 and the SCTR promoter was also observed following chromatin immunoprecipitation assay. In vivo, osmotic stress up-regulates the SCTR gene in the kidney cortex and medulla of wild-type mice, but does not do so in NFAT5(+/-) animals. Hence, this study provides comprehensive information on how NFAT5 regulates SCTR expression in different osmotic environments.
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Affiliation(s)
- Oscar W H Chua
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Kenneth K L Wong
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Ben C Ko
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China
| | - Sookja K Chung
- Department of Anatomy and the State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China; HBHA Research Center, Faculty of Medicine, The University of Hong Kong, China
| | - Billy K C Chow
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China
| | - Leo T O Lee
- Faculty of Health Sciences, University of Macau, Taipa, Macau, China.
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9
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Gordon R, Park SY, Schuller-Levis G, Park E. A novel cysteine sulfinic Acid decarboxylase knock-out mouse: pathology of the kidney and lung in newborn pups. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 803:17-28. [PMID: 25833484 DOI: 10.1007/978-3-319-15126-7_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Ronald Gordon
- Department of Pathology, Mt. Sinai School of Medicine, New York, NY, 10029, USA
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Extracellular osmolarity regulates matrix homeostasis in the intervertebral disc and articular cartilage: evolving role of TonEBP. Matrix Biol 2014; 40:10-6. [PMID: 25172826 PMCID: PMC4390124 DOI: 10.1016/j.matbio.2014.08.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/18/2014] [Accepted: 08/19/2014] [Indexed: 12/20/2022]
Abstract
Degeneration of the intervertebral disc is characterized by changes in proteoglycan status, loss of bound water molecules, decreased tissue osmotic pressure and a resulting mechanical failure of the disc. A similar spectrum of changes is evident in osteoarthritic articular cartilage. When healthy, resident cells in these skeletal tissues respond to applied mechanical loads by regulating their own osmotic state and the hydration of the extracellular matrix. The transcription factor Tonicity-Responsive Enhancer Binding Protein (TonEBP or NFAT5) is known to mediate the osmoadaptive response in these and other tissues. While the molecular basis of how osmotic loading controls matrix homeostasis is not completely understood, TonEBP regulates the expression of aggrecan and β1,3-glucoronosyltransferase in nucleus pulposus cells, in addition to targets that allow for survival under hypertonic stress. Moreover, in chondrocytes, TonEBP controls expression of several collagen subtypes and Sox9, a master regulator of aggrecan and collagen II expression. Thus, TonEBP-mediated regulation of the matrix composition allows disc cells and chondrocytes to modify the extracellular osmotic state itself. On the other hand, TonEBP in immune cells induces expression of TNF-α, IL-6 and MCP-1, pro-inflammatory molecules closely linked to matrix catabolism and pathogenesis of both disc degeneration and osteoarthritis, warranting investigations of this aspect of TonEBP function in skeletal cells. In summary, the TonEBP system, through its effects on extracellular matrix and osmoregulatory genes can be viewed primarily as a protective or homeostatic response to physiological loading.
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Park J, Kim H, Park SY, Lim SW, Kim YS, Lee DH, Roh GS, Kim HJ, Kang SS, Cho GJ, Jeong BY, Kwon HM, Choi WS. Tonicity-responsive enhancer binding protein regulates the expression of aldose reductase and protein kinase C δ in a mouse model of diabetic retinopathy. Exp Eye Res 2014; 122:13-9. [PMID: 24631337 DOI: 10.1016/j.exer.2014.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/24/2014] [Accepted: 03/02/2014] [Indexed: 12/25/2022]
Abstract
Recent studies revealed that Tonicity-responsive enhancer binding protein (TonEBP) directly regulates the transcription of aldose reductase (AR), which catalyzes the first step of the polyol pathway of glucose metabolism. Activation of protein kinase C δ (PKCδ) is dependent on AR and it has been linked to diabetic complications. However, whether TonEBP affects expressions of AR and PKCδ in diabetic retinopathy was not clearly shown. In this study, we used TonEBP heterozygote mice to study the role of TonEBP in streptozotocin (STZ)-induced diabetic retinopathy. We performed immunofluorescence staining and found that retinal expressions of AR and PKCδ were significantly reduced in the heterozygotes compared to wild type littermates, particularly in ganglion cell layer. To examine further the effect of TonEBP reduction in retinal tissues, we performed intravitreal injection of TonEBP siRNA and confirmed the decrease in AR and PKCδ levels. In addition, we found that a proapoptotic factor, Bax level was reduced and a survival factor, Bcl2 level was increased after injection of TonEBP siRNA, indicating that TonEBP mediates apoptotic cell death. In parallel, TonEBP siRNA was applied to the in vitro human retinal pigment epithelial (ARPE-19) cells cultured in high glucose media. We have consistently found the decrease in AR and PKCδ levels and changes in apoptotic factors for survival. Together, these results clearly demonstrated that hyperglycemia-induced TonEBP plays a crucial role in increasing AR and PKCδ levels and leading to apoptotic death. Our findings suggest that TonEBP reduction is an effective therapeutic strategy for diabetic retinopathy.
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Affiliation(s)
- Jeongsook Park
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea; Department of Food & Nutrition, College of Natural Sciences, Gyeongsang National University, Jinju, Gyeongnam, Republic of Korea
| | - Hwajin Kim
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - So Yun Park
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Sun Woo Lim
- Transplant Research Center, The of Catholic University of Korea, Seoul, Republic of Korea
| | - Yoon Sook Kim
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Dong Hoon Lee
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Gu Seob Roh
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Hyun Joon Kim
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Sang Soo Kang
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Gyeong Jae Cho
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Bo-Young Jeong
- Department of Food & Nutrition, College of Natural Sciences, Gyeongsang National University, Jinju, Gyeongnam, Republic of Korea
| | - H Moo Kwon
- School of Nano-Biotechnology and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Wan Sung Choi
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea.
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12
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Wright EM. Glucose transport families SLC5 and SLC50. Mol Aspects Med 2013; 34:183-96. [DOI: 10.1016/j.mam.2012.11.002] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 10/04/2012] [Indexed: 01/15/2023]
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13
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Betaine stabilizes cell volume and protects against apoptosis in human corneal epithelial cells under hyperosmotic stress. Exp Eye Res 2013; 108:33-41. [DOI: 10.1016/j.exer.2012.12.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 11/17/2012] [Accepted: 12/04/2012] [Indexed: 11/19/2022]
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Halterman JA, Kwon HM, Leitinger N, Wamhoff BR. NFAT5 expression in bone marrow-derived cells enhances atherosclerosis and drives macrophage migration. Front Physiol 2012; 3:313. [PMID: 22934063 PMCID: PMC3429083 DOI: 10.3389/fphys.2012.00313] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 07/17/2012] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE We have previously shown that the transcription factor, nuclear factor of activated T-cells 5 (NFAT5), regulates vascular smooth muscle cell phenotypic modulation, but the role of NFAT5 in atherosclerosis is unknown. Our main objective was to determine if NFAT5 expression in bone marrow (BM)-derived cells altered atherosclerotic development and macrophage function. METHODS AND RESULTS NFAT5(+/-)ApoE(-/-) mice were generated for in vivo atherosclerosis studies. Following high fat diet feeding, en face analysis of the thoracic aorta established that genome-wide NFAT5 haploinsufficiency reduced atherosclerotic lesion formation by 73%. BM transplant studies revealed that transplantation of NFAT5(+/-)ApoE(-/-) marrow into NFAT5(+/+)ApoE(-/-) mice resulted in a similar 86% reduction in lesion formation. In vitro functional analysis of BM-derived macrophages demonstrated that NFAT5 is required for macrophage migration, which is a key event in the propagation of atherosclerosis. CONCLUSION We have identified NFAT5 in BM-derived cells as a positive regulator of atherosclerotic lesion formation and macrophage function in the vasculature.
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Affiliation(s)
- Julia A Halterman
- Department of Pharmacology, University of Virginia, Charlottesville VA, USA
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Choi HJ, Yoon YJ, Kwon YK, Lee YJ, Chae S, Hwang D, Hwang GS, Kwon TH. Patterns of gene and metabolite define the effects of extracellular osmolality on kidney collecting duct. J Proteome Res 2012; 11:3816-28. [PMID: 22686594 DOI: 10.1021/pr300309d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
To investigate the effects of changes in extracellular osmolality on the function of kidney collecting duct cells, particularly on water and sodium reabsorption in the conditions of diuresis and antidiuresis, we generated transcriptome and metabolome profiles of primary cultured inner medullary collecting duct (IMCD) cells. They were grown in hyperosmolar culture medium (640 mOsm) for 4 days and then exposed to either reduced (300 mOsm) or same osmolality for 1 or 2 days more. Integrated analysis of the transcriptome and metabolome revealed that decreased extracellular osmolality was associated with decreased levels of organic osmolytes, glucose, intermediates of citric acid cycle, and branched-chain amino acids (BCAA) in IMCD cells, along with significantly decreased gene expression and protein abundance of P-type transporters (ATP1B1), ABC transporters (ABCC5 and ABCG1), and insulin signaling pathways (IRS2). Quantitative real-time RT-PCR and semiquantitative immunoblotting confirmed the changes of transcript levels of differentially expressed genes and protein levels. Taken together, integrated analysis of omics data demonstrated that water and sodium reabsorption could be reduced by decreased extracellular osmolality per se, through decreased levels of ABC transporters and IRS2, which play a potential role in the transport of organic osmolytes, BCAA, glucose, and trafficking of epithelial sodium channel.
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Affiliation(s)
- Hyo-Jung Choi
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Taegu, Korea
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Dubois JM, Rouzaire-Dubois B. Roles of cell volume in molecular and cellular biology. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 108:93-7. [PMID: 22192789 DOI: 10.1016/j.pbiomolbio.2011.12.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 12/05/2011] [Accepted: 12/06/2011] [Indexed: 01/17/2023]
Abstract
Extracellular tonicity and volume regulation control a great number of molecular and cellular functions including: cell proliferation, apoptosis, migration, hormone and neuromediator release, gene expression, ion channel and transporter activity and metabolism. The aim of this review is to describe these effects and to determine if they are direct or are secondarily the result of the activity of second messengers.
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Affiliation(s)
- Jean-Marc Dubois
- CNRS, Institut de Neurobiologie Alfred Fessard-FRC2118, Gif sur Yvette F-91198, France.
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17
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Halterman JA, Kwon HM, Wamhoff BR. Tonicity-independent regulation of the osmosensitive transcription factor TonEBP (NFAT5). Am J Physiol Cell Physiol 2011; 302:C1-8. [PMID: 21998140 DOI: 10.1152/ajpcell.00327.2011] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Tonicity-responsive enhancer binding protein (TonEBP/nuclear factor of activated T-cells 5 [NFAT5]) is a Rel homology transcription factor classically known for its osmosensitive role in regulating cellular homeostasis during states of hypo- and hypertonic stress. A recently growing body of research indicates that TonEBP is not solely regulated by tonicity, but that it can be stimulated by various tonicity-independent mechanisms in both hypertonic and isotonic tissues. Physiological and pathophysiological stimuli such as cytokines, growth factors, receptor and integrin activation, contractile agonists, ions, and reactive oxygen species have been implicated in the positive regulation of TonEBP expression and activity in diverse cell types. These new data demonstrate that tonicity-independent stimulation of TonEBP is critical for tissue-specific functions like enhanced cell survival, migration, proliferation, vascular remodeling, carcinoma invasion, and angiogenesis. Continuing research will provide a better understanding as to how these and other alternative TonEBP stimuli regulate gene expression in both health and disease.
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Affiliation(s)
- Julia A Halterman
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, USA
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Integrated analysis of miRNA and mRNA expression in childhood medulloblastoma compared with neural stem cells. PLoS One 2011; 6:e23935. [PMID: 21931624 PMCID: PMC3170291 DOI: 10.1371/journal.pone.0023935] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 07/28/2011] [Indexed: 11/29/2022] Open
Abstract
Medulloblastoma (MB) is the most common malignant brain tumor in children and a leading cause of cancer-related mortality and morbidity. Several molecular sub-types of MB have been identified, suggesting they may arise from distinct cells of origin. Data from animal models indicate that some MB sub-types arise from multipotent cerebellar neural stem cells (NSCs). Hence, microRNA (miRNA) expression profiles of primary MB samples were compared to CD133+ NSCs, aiming to identify deregulated miRNAs involved in MB pathogenesis. Expression profiling of 662 miRNAs in primary MB specimens, MB cell lines, and human CD133+ NSCs and CD133− neural progenitor cells was performed by qRT-PCR. Clustering analysis identified two distinct sub-types of MB primary specimens, reminiscent of sub-types obtained from their mRNA profiles. 21 significantly up-regulated and 12 significantly down-regulated miRNAs were identified in MB primary specimens relative to CD133+ NSCs (p<0.01). The majority of up-regulated miRNAs mapped to chromosomal regions 14q32 and 17q. Integration of the predicted targets of deregulated miRNAs with mRNA expression data from the same specimens revealed enrichment of pathways regulating neuronal migration, nervous system development and cell proliferation. Transient over-expression of a down-regulated miRNA, miR-935, resulted in significant down-regulation of three of the seven predicted miR-935 target genes at the mRNA level in a MB cell line, confirming the validity of this approach. This study represents the first integrated analysis of MB miRNA and mRNA expression profiles and is the first to compare MB miRNA expression profiles to those of CD133+ NSCs. We identified several differentially expressed miRNAs that potentially target networks of genes and signaling pathways that may be involved in the transformation of normal NSCs to brain tumor stem cells. Based on this integrative approach, our data provide an important platform for future investigations aimed at characterizing the role of specific miRNAs in MB pathogenesis.
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Different effects of CsA and FK506 on aquaporin-2 abundance in rat primary cultured collecting duct cells. Pflugers Arch 2011; 462:611-22. [PMID: 21773745 DOI: 10.1007/s00424-011-0994-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 07/04/2011] [Accepted: 07/06/2011] [Indexed: 10/18/2022]
Abstract
Calcineurin (Cn) inhibitors (CnI) such as cyclosporine A (CsA) and FK506 are nephrotoxic immunosuppressant drugs, which decrease tubular function. Here, we examined the direct effect of CnI on aquaporin-2 (AQP2) expression in rat primary cultured inner medullary collecting duct cells. CsA (0.5-5 μM) but not FK 506 (0.01-1 μM) decreased expression of AQP2 protein and messenger RNA (mRNA) in a concentration and time dependent manner, without affecting mRNA stability. This effect was observed despite similar inhibition of Cn activity by both CnI, thereby suggesting that the CsA-dependent decrease in AQP2 expression was Cn independent. Another inhibitor of cyclophilin A, the primary intracellular target of CsA, had no effect on AQP2 expression. In order to investigate the mechanism of decreased AQP2 transcription, we studied activation status of two suggested transcriptional regulators of AQP2, cAMP-responsive element binding protein (CREB), and tonicity enhancer binding protein (TonEBP). Localization of TonEBP, as well as TonEBP-mediated gene transcription, was not affected by CsA. Phosphorylation of CREB at an activating phosphorylation site (S133) was decreased by CsA, but not by FK506. However, both CnI did not affect cellular cAMP levels. We show that CsA decreases transcription of AQP2, a process that is in part independent of Cn or cyclophilin A and suggests dependence on decreased activity of CREB.
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20
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Cell cycle control and DNA damage response of conditionally immortalized urothelial cells. PLoS One 2011; 6:e16595. [PMID: 21305048 PMCID: PMC3030598 DOI: 10.1371/journal.pone.0016595] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 01/06/2011] [Indexed: 11/25/2022] Open
Abstract
Background Children with complex urogenital anomalies often require bladder reconstruction. Gastrointestinal tissues used in bladder augmentations exhibit a greatly increased risk of malignancy, and the bladder microenvironment may play a role in this carcinogenesis. Investigating the influences of the bladder microenvironment on gastrointestinal and urothelial cell cycle checkpoint activation and DNA damage response has been limited by the lack of an appropriate well-differentiated urothelial cell line system. Methodology/Principal Findings To meet this need, we have developed a well-differentiated conditionally immortalized urothelial cell line by isolating it from the H-2Kb-tsA58 transgenic mouse. These cells express a thermosensitive SV40 large T antigen that can be deactivated by adjustment of cell culture conditions, allowing the cell line to regain normal control of the cell cycle. The isolated urothelial cell line demonstrates a polygonal, dome-shaped morphology, expresses cytokeratin 18, and exhibits well-developed tight junctions. Adaptation of the urothelial cell line to hyperosmolal culture conditions induces expression of both cytokeratin 20 and uroplakin II, markers of a superficial urothelial cell or “umbrella cell.” This cell line can be maintained indefinitely in culture under permissive conditions but when cultured under non-permissive conditions, large T antigen expression is reduced substantially, leading to increased p53 activity and reduced cellular proliferation. Conclusions/Significance This new model of urothelial cells, along with gastrointestinal cell lines previously derived from the H-2Kb-tsA58 transgenic mouse, will be useful for studying the potential mechanisms of carcinogenesis of the augmented bladder.
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Abstract
Taurine participates in a number of different physiologic and biologic processes in the kidney, often reflected by urinary excretion patterns. The kidney is key to aspects of taurine body pool size and homeostasis. This review will examine the renal-taurine interactions relative to ion reabsorption; renal blood flow and renal vascular endothelial function; antioxidant properties, especially in the glomerulus; and the role of taurine in ischemia and reperfusion injury. In addition, taurine plays a role in the renal cell cycle and apoptosis, and functions as an osmolyte during the stress response. The role of the kidney in adaptation to variations in dietary taurine intake and the regulation of taurine body pool size are described. Finally, the protective function of taurine against several kidney diseases is reviewed.
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Affiliation(s)
- Russell W Chesney
- Department of Pediatrics, University of Tennessee Health Science Center, and the Children's Foundation Research Center at Le Bonheur Children's Medical Center, 50 N, Dunlap, Memphis, Tennessee 38103, USA.
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Lanaspa MA, Andres-Hernando A, Li N, Rivard CJ, Cicerchi C, Roncal-Jimenez C, Schrier RW, Berl T. The expression of aquaporin-1 in the medulla of the kidney is dependent on the transcription factor associated with hypertonicity, TonEBP. J Biol Chem 2010; 285:31694-703. [PMID: 20639513 DOI: 10.1074/jbc.m109.093690] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Expression of aquaporin-1 (AQP1) and -2 (AQP2) channels in the kidney are critical for the maintenance of water homeostasis and the operation of the urinary concentrating mechanism. Hypertonic stress induced in inner medullary (IMCD3) cells by addition of NaCl to the medium substantially up-regulated the mRNA and protein expression of AQP1, suggesting that its activation occurs at a transcriptional and a translational levels. In contrast, no up-regulation of AQP1 was observed when these cells were exposed to the same tonicity by addition of urea. To explore the transcriptional activation of aqp1 under hypertonic stress, we examined the role of the transcription factor associated with hypertonicity, TonEBP. Treatment of IMCD3 cells with the TonEBP inhibitor rottlerin or silencing its expression with specific shRNA technology led to a substantial reduction in AQP1 expression under hypertonic conditions. Moreover, we defined a conserved TonEBP binding site located 811 bp upstream of the aqp1 exon that is essential for its expression. Single site-directed mutation of this TonE site led to a 54 ± 5% (p < 0.01) decrease in AQP1 luciferase-driven activity under hypertonic stress. TonEBP mutant mice display marked decrement in the expression of AQP1 in the inner medulla. In conclusion, these data demonstrate that TonEBP is necessary for the regulation of AQP1 expression in the inner medulla of the kidney under hypertonic conditions.
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Affiliation(s)
- Miguel A Lanaspa
- Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado, Denver, Colorado 80045, USA
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Cotton LM, Rodriguez CM, Suzuki K, Orgebin-Crist MC, Hinton BT. Organic cation/carnitine transporter, OCTN2, transcriptional activity is regulated by osmotic stress in epididymal cells. Mol Reprod Dev 2009; 77:114-25. [DOI: 10.1002/mrd.21122] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Lanaspa MA, Andres-Hernando A, Rivard CJ, Dai Y, Li N, Berl T. ZAC1 is up-regulated by hypertonicity and decreases sorbitol dehydrogenase expression, allowing accumulation of sorbitol in kidney cells. J Biol Chem 2009; 284:19974-81. [PMID: 19423711 PMCID: PMC2740423 DOI: 10.1074/jbc.m109.001792] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 05/01/2009] [Indexed: 01/09/2023] Open
Abstract
Affymetrix GeneChip technology was employed to detect differentially expressed genes in inner medullary collecting duct (IMCD3) cells grown under isotonic and hypertonic conditions. A marked up-regulation was found for the zinc-finger protein ZAC1 under hypertonic stress (219-fold, p < 0.001). Changes in expression for ZAC1 were verified by quantitative PCR for message and Western blotting for protein. In mouse and human kidney tissues, ZAC1 expression was substantial in the papilla and was absent in the cortex. Furthermore, ZAC1 expression significantly increased in the papilla of mice following 36 h of fluid restriction and decreased in polyuric mice consuming sucrose in water. Because ZAC1 has been described to be a potential negative regulator of sorbitol dehydrogenase (SDH) in hippocampal cells, we examined whether this relationship also occurs in kidney cells under hypertonic stress. We found that stable IMCD3 clones silenced for ZAC1 to varying levels demonstrated an inverse effect on SDH expression. ZAC1 binds to a consensus repression site within the promoter of SDH, pointing to a mechanism whereby ZAC1 acts by repressing SDH transcriptional activity during hypertonic conditions. Taken together, these data strongly suggest that ZAC1 is up-regulated under hypertonic stress and negatively regulates expression of SDH, allowing for accumulation of sorbitol as a compatible organic osmolyte.
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Affiliation(s)
- Miguel A. Lanaspa
- From the Department of Renal Diseases and Hypertension, University of Colorado Health Sciences Center, Aurora, Colorado 80045
| | - Ana Andres-Hernando
- From the Department of Renal Diseases and Hypertension, University of Colorado Health Sciences Center, Aurora, Colorado 80045
| | - Christopher J. Rivard
- From the Department of Renal Diseases and Hypertension, University of Colorado Health Sciences Center, Aurora, Colorado 80045
| | - Yue Dai
- From the Department of Renal Diseases and Hypertension, University of Colorado Health Sciences Center, Aurora, Colorado 80045
| | - Nanxing Li
- From the Department of Renal Diseases and Hypertension, University of Colorado Health Sciences Center, Aurora, Colorado 80045
| | - Tomas Berl
- From the Department of Renal Diseases and Hypertension, University of Colorado Health Sciences Center, Aurora, Colorado 80045
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Rødgaard T, Schou K, Friis MB, Hoffmann EK. Does the intracellular ionic concentration or the cell water content (cell volume) determine the activity of TonEBP in NIH3T3 cells? Am J Physiol Cell Physiol 2008; 295:C1528-34. [DOI: 10.1152/ajpcell.00081.2008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The transcription factor, tonicity-responsive enhancer binding protein (TonEBP), is involved in the adaptive response against hypertonicity. TonEBP regulates the expression of genes that catalyze the accumulation of osmolytes, and its transcriptional activity is increased by hypertonicity. The goal of the present investigation was to investigate whether cell shrinkage or high intracellular ionic concentration induced the activation of TonEBP. We designed a model system for isotonically shrinking cells over a prolonged period of time. Cells swelled in hypotonic medium and performed a regulatory volume decrease. Upon return to the original isotonic medium, cells shrank initially, followed by a regulatory volume increase. To maintain cell shrinkage, the RVI process was inhibited as follows: ethyl-isopropyl-amiloride inhibited the Na+/H+ antiport, bumetanide inhibited the Na+-K+-2Cl− cotransporter, and gadolinium inhibited shrinkage-activated Na+ channels. Cells remained shrunken for at least 4 h (isotonically shrunken cells). The activity of TonEBP was investigated with a Luciferase assay after isotonic shrinkage and after shrinkage in a high-NaCl hypertonic medium. We found that TonEBP was strongly activated after 4 and 16 h in cells in high-NaCl hypertonic medium, but not after 4 or 16 h in isotonically shrunken cells. Cells treated with high-NaCl hypertonic medium for 4 h had significantly higher intracellular concentrations of both K+ and Na+ than isotonically shrunken cells. This strongly suggested that an increase in intracellular ionic concentration and not cell shrinkage is involved in TonEBP activation.
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Bissonnette P, Lahjouji K, Coady MJ, Lapointe JY. Effects of hyperosmolarity on the Na+-myo-inositol cotransporter SMIT2 stably transfected in the Madin-Darby canine kidney cell line. Am J Physiol Cell Physiol 2008; 295:C791-9. [DOI: 10.1152/ajpcell.00390.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Myo-inositol (MI) is a compatible osmolyte used by cells to compensate for changes in the osmolarity of their surrounding milieu. In kidney, the basolateral Na+-MI cotransporter (SMIT1) and apical SMIT2 proteins are homologous cotransporters responsible for cellular uptake of MI. It has been shown in the Madin-Darby canine kidney (MDCK) cell line that SMIT1 expression was under the control of the tonicity-sensitive transcription factor, tonicity-responsive enhancer binding protein (TonEBP). We used an MDCK cell line stably transfected with SMIT2 to determine whether variations in external osmolarity could also affect SMIT2 function. Hyperosmotic conditions (+200 mosM raffinose or NaCl but not urea) generated an increase in SMIT2-specific MI uptake by three- to ninefold in a process that required protein synthesis. Using quantitative RT-PCR, we have determined that hyperosmotic conditions augment both the endogenous SMIT1 and the transfected SMIT2 mRNAs. Transport activities for both SMIT1 and SMIT2 exhibited differences in their respective induction profiles for both their sensitivities to raffinose, as well as in their time course of induction. Application of MG-132, which inhibits nuclear translocation of TonEBP, showed that the effect of osmolarity on transfected SMIT2 was unrelated to TonEBP, unlike the effect observed with SMIT1. Inhibition studies involving the hyperosmolarity-related MAPK suggested that p38 and JNK play a role in the induction of SMIT2. Further studies have shown that hyperosmolarity also upregulates another transfected transporter (Na+-glucose), as well as several endogenously expressed transport systems. This study shows that hyperosmolarity can stimulate transport in a TonEBP-independent manner by increasing the amount of mRNA derived from an exogenous DNA segment.
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Buccafusca R, Venditti CP, Kenyon LC, Johanson RA, Van Bockstaele E, Ren J, Pagliardini S, Minarcik J, Golden JA, Coady MJ, Greer JJ, Berry GT. Characterization of the null murine sodium/myo-inositol cotransporter 1 (Smit1 or Slc5a3) phenotype: myo-inositol rescue is independent of expression of its cognate mitochondrial ribosomal protein subunit 6 (Mrps6) gene and of phosphatidylinositol levels in neonatal brain. Mol Genet Metab 2008; 95:81-95. [PMID: 18675571 DOI: 10.1016/j.ymgme.2008.05.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 05/30/2008] [Accepted: 05/30/2008] [Indexed: 12/13/2022]
Abstract
Ablation of the murine Slc5a3 gene results in severe myo-inositol (Ins) deficiency and congenital central apnea due to abnormal respiratory rhythmogenesis. The lethal knockout phenotype may be rescued by supplementing the maternal drinking water with 1% Ins. In order to test the hypothesis that Ins deficiency leads to inositide deficiencies, which are corrected by prenatal treatment, we measured the effects of Ins rescue on Ins, phosphatidylinositol (PtdIns) and myo-inositol polyphosphate levels in brains of E18.5 knockout fetuses. As the Slc5a3 gene structure is unique in the sodium/solute cotransporter (SLC5) family, and exon 1 is shared with the mitochondrial ribosomal protein subunit 6 (Mrps6) gene, we also sought to determine whether expression of its cognate Mrps6 gene is abnormal in knockout fetuses. The mean level of Ins was increased by 92% in brains of rescued Slc5a3 knockout fetuses (0.48 versus 0.25 nmol/mg), but was still greatly reduced in comparison to wildtype (6.97 nmol/mg). The PtdIns, InsP(5) and InsP(6) levels were normal without treatment. Mrps6 gene expression was unaffected in the E18.5 knockout fetuses. This enigmatic model is not associated with neonatal PtdIns deficiency and rescue of the phenotype may be accomplished without restoration of Ins. The biochemical mechanism that both uniformly leads to death and allows for Ins rescue remains unknown. In conclusion, in neonatal brain tissue, Mrps6 gene expression may not be contingent on function of its embedded Slc5a3 gene, while inositide deficiency may not be the mechanism of lethal apnea in null Slc5a3 mice.
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Affiliation(s)
- Roberto Buccafusca
- Department of Pediatrics, Thomas Jefferson University, Philadelphia, PA, USA
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Andres-Hernando A, Lanaspa MA, Rivard CJ, Berl T. Nucleoporin 88 (Nup88) is regulated by hypertonic stress in kidney cells to retain the transcription factor tonicity enhancer-binding protein (TonEBP) in the nucleus. J Biol Chem 2008; 283:25082-90. [PMID: 18606815 DOI: 10.1074/jbc.m802381200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Antibody microarray technology identified Nup88 (nucleoporin 88) as a highly up-regulated protein in response to osmotic stress in inner medullary collecting duct (IMCD3) cells. Changes in expression were verified by Western blot and quantitative PCR for protein and message expression. In mouse and human kidney, Nup88 expression was substantial in the papilla, whereas it was nearly absent in the cortex. Furthermore, the expression of Nup88 increased 410.4 +/- 22% in the papilla of mice after 36 h of thirsting. Nup88 protein expression in IMCD3 cells was significantly up-regulated in the first 8 h following exposure to acute osmotic stress, indicating that Nup88 is an early response protein. To define the function of Nup88 in the osmotic stress response, the transcription factor associated with hypertonicity, tonicity enhancer-binding protein (TonEBP), was cloned upstream of the green fluorescent protein. Employing this construct, we demonstrate that silencing Nup88 in IMCD3 cells acutely stressed to hypertonic conditions reduces nuclear retention of TonEBP, resulting in a substantial blunting in transcription of important osmotic stress response target genes and reduced cell viability. Finally, we show that in IMCD3 cells, nuclear export of TonEBP under isotonic conditions involves CRM-1 but under hypertonic stress is CRM1-independent. Our data, therefore, suggest that Nup88 is up-regulated in response to hypertonic stress and acts to retain TonEBP in the nucleus, activating transcription of critical osmoprotective genes.
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Affiliation(s)
- Ana Andres-Hernando
- Division of Renal Diseases and Hypertension, School of Medicine, University Colorado Health Sciences Center, Denver, Colorado 80262, USA
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29
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Xu S, Wong CCL, Tong EHY, Chung SSM, Yates JR, Yin Y, Ko BCB. Phosphorylation by casein kinase 1 regulates tonicity-induced osmotic response element-binding protein/tonicity enhancer-binding protein nucleocytoplasmic trafficking. J Biol Chem 2008; 283:17624-34. [PMID: 18411282 DOI: 10.1074/jbc.m800281200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The osmotic response element-binding protein (OREBP), also known as tonicity enhancer-binding protein (TonEBP) or NFAT5, is the only known osmo-sensitive transcription factor that mediates cellular adaptations to extracellular hypertonic stress. Although it is well documented that the subcellular localization and transactivation activity of OREBP/TonEBP are tightly regulated by extracellular tonicity, the molecular mechanisms involved remain elusive. Here we show that nucleocytoplasmic trafficking of OREBP/TonEBP is regulated by the dual phosphorylation of Ser-155 and Ser-158. Alanine scanning mutagenesis revealed that Ser-155 is an essential residue that regulates OREBP/TonEBP nucleocytoplasmic trafficking. Tandem mass spectrometry revealed that Ser-155 and Ser-158 of OREBP/TonEBP are both phosphorylated in living cells under hypotonic conditions. In vitro phosphorylation assays further suggest that phosphorylation of the two serine residues proceeds in a hierarchical manner with phosphorylation of Ser-155 priming the phosphorylation of Ser-158 and that these phosphorylations are essential for nucleocytoplasmic trafficking of the transcription factor. Finally, we have shown that the pharmacological inhibition of casein kinase 1 (CK1) abolishes the phosphorylation of Ser-158 and impedes OREBP/TonEBP nuclear export and that recombinant CK1 phosphorylates Ser-158. Knockdown of CK1alpha1L, a novel isoform of CK1, inhibits hypotonicity-induced OREBP/TonEBP nuclear export. Together these data highlight the importance of Ser-155 and Ser-158 in the nucleocytoplasmic trafficking of OREBP/TonEBP and indicate that CK1 plays a major role in regulating this process.
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Affiliation(s)
- SongXiao Xu
- The State Key Laboratory in Oncology in South China, Chinese University of Hong Kong, Hong Kong, China
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30
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Selective tonicity-induced expression of the neutral amino-acid transporter SNAT2 in oligodendrocytes in rat brain following systemic hypertonicity. Neuroscience 2008; 153:95-107. [DOI: 10.1016/j.neuroscience.2008.01.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 12/20/2007] [Accepted: 01/18/2008] [Indexed: 12/22/2022]
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31
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Maallem S, Wierinckx A, Lachuer J, Kwon MH, Tappaz ML. Gene expression profiling in brain following acute systemic hypertonicity: novel genes possibly involved in osmoadaptation. J Neurochem 2008; 105:1198-211. [PMID: 18194432 DOI: 10.1111/j.1471-4159.2008.05222.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In brain osmoprotective genes known to be involved in cellular osmoadaptation to hypertonicity, as well as the related transcription factor tonicity-responsive enhancer binding protein (TonEBP) are only expressed in some cell subsets. In the search for other genes possibly involved in osmoadaptation of brain cells we have analyzed, through microarray, the transcriptional profile of forebrain from rats subjected to 45 min, 90 min, and 6 h systemic hypertonicity. Microarray data were validated by quantitative real-time PCR. Around 23 000 genes gave a reliable hybridization signal. The number of genes showing a higher expression increased from around 15 (45 min) up to nearly 200 (6 h). Among about 30 immediate early genes (IEGs) encoding transcription factors, only Atf3, Verge, and Klf4 showed a rapid increased expression. TonEBP-mRNA tissue level and TonEBP-mRNA labeling in neurons remained unchanged whereas TonEBP labeling was rapidly increased in neurons. Sodium-dependent neutral amino acid transporter-2 (SNAT2) encoded by gene Slc38a2 showed a delayed increased expression. The rapid tonicity-induced activation of Atf3, Verge, and Klf4 may regulate genes involved in osmoadaptation. Nfat5 encoding TonEBP is not an IEG and the early tonicity-induced expression of TonEBP in neurons may result from translational activation. Increased expression of sodium-dependent neutral amino-acid transporter 2 may lead to the cellular accumulation of amino acids for adaptation to hypertonicity.
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Affiliation(s)
- Saïd Maallem
- Unité INSERM 433, Neurobiologie Experimentale et Physiopathologie, Faculté de Médecine RTH Laennec, Rue Guillaume Paradin, Lyon, Cedex, France
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32
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Singer TD, Raptis S, Sathiyaa R, Nichols JW, Playle RC, Vijayan MM. Tissue-specific modulation of glucocorticoid receptor expression in response to salinity acclimation in rainbow trout. Comp Biochem Physiol B Biochem Mol Biol 2006; 146:271-8. [PMID: 17215158 DOI: 10.1016/j.cbpb.2006.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Revised: 11/03/2006] [Accepted: 11/04/2006] [Indexed: 11/25/2022]
Abstract
While studies clearly point to a role for cortisol signaling in seawater adaptation, very little is known about salinity impact on glucocorticoid receptor (GR) expression in fish. To this end, we investigated the temporal GR expression in the gill and liver of rainbow trout (Oncorhynchus mykiss) to salinity exposure. Trout were subjected to gradual salinity increases (11 ppt for 1 d, 17 ppt for 2 d and 23 ppt for 2 d) over a five day period. Gill Na(+), K(+)-ATPase alpha-subunit mRNA showed a transient elevation with salinity exposure, while gill cystic fibrosis transmembrane conductance regulator mRNA was not significantly affected by salinity. Liver PEPCK transcript levels showed a transient increase at day 1, but not at day 3 or day 5 of salinity exposure, while the activity of this enzyme was significantly depressed at all time points. Liver glycogen content was also significantly reduced by salinity exposure compared to the freshwater group. Gill GR transcript levels were 3-fold greater upon salinity exposure and this level was maintained over the 5 day period, while gill GR protein content remained unchanged except for a significant drop at day 1 of salinity exposure. Liver GR transcript levels showed no significant change with salinity exposure, while GR protein content was transiently elevated at day 3, but not at day 1 or day 5 of salinity exposure. The tissue-specific GR transcript response in the gill leads us to hypothesize a role for osmosensory signal transduction pathway in the regulation of GR expression in fish. Collectively, salinity exposure modulates GR expression and glucocorticoid signaling in rainbow trout.
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Affiliation(s)
- Thomas D Singer
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
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33
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Tong EHY, Guo JJ, Huang AL, Liu H, Hu CD, Chung SSM, Ko BCB. Regulation of nucleocytoplasmic trafficking of transcription factor OREBP/TonEBP/NFAT5. J Biol Chem 2006; 281:23870-9. [PMID: 16782704 DOI: 10.1074/jbc.m602556200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The osmotic response element-binding protein (OREBP), also known as tonicity enhancer-binding protein (TonEBP) or NFAT5, regulates the hypertonicity-induced expression of a battery of genes crucial for the adaptation of mammalian cells to extracellular hypertonic stress. The activity of OREBP/TonEBP is regulated at multiple levels, including nucleocytoplasmic trafficking. OREBP/TonEBP protein can be detected in both the cytoplasm and nucleus under isotonic conditions, although it accumulates exclusively in the nucleus or cytoplasm when subjected to hypertonic or hypotonic challenges, respectively. Using immunocytochemistry and green fluorescent protein fusions, the protein domains that determine its subcellular localization were identified and characterized. We found that OREBP/TonEBP nuclear import is regulated by a nuclear localization signal. However, under isotonic conditions, nuclear export of OREBP/TonEBP is mediated by a CRM1-dependent, leucine-rich canonical nuclear export sequence (NES) located in the N terminus. Disruption of NES by site-directed mutagenesis yielded a mutant OREBP/TonEBP protein that accumulated in the nucleus under isotonic conditions but remained a target for hypotonicity-induced nuclear export. More importantly, a putative auxiliary export domain distal to the NES was identified. Disruption of the auxiliary export domain alone is sufficient to abolish the nuclear export of OREBP/TonEBP induced by hypotonicity. By using bimolecular fluorescence complementation assay, we showed that CRM1 interacts with OREBP/TonEBP, but not with a mutant protein deficient in NES. Our findings provide insight into how nucleocytoplasmic trafficking of OREBP/TonEBP is regulated by changes in extracellular tonicity.
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Affiliation(s)
- Edith H Y Tong
- Department of Chemistry, University of Hong Kong, Hong Kong Special Administrative Region, China
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34
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Kempson SA, Edwards JM, Sturek M. Inhibition of the renal betaine transporter by calcium ions. Am J Physiol Renal Physiol 2006; 291:F305-13. [PMID: 16525159 DOI: 10.1152/ajprenal.00428.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic upregulation of the renal betaine/GABA transporter (BGT1) by hypertonic stress has been well documented, but it is not known whether BGT1 can be regulated acutely after insertion in the basolateral plasma membrane. Related transporters, such as the rat brain GABA transporter, can be rapidly removed from the plasma membrane through activation of G protein-coupled receptors. The goal of the present study was to determine whether acute changes in extracellular and/or intracellular Ca2+will regulate BGT1 transport activity at the plasma membrane level in Madin-Darby canine kidney cells subjected to 24-h hypertonic stress. After brief pretreatment with a Ca2+-free solution, the addition of extracellular Ca2+in the transport assay produced dose-dependent inhibition of Na+-GABA cotransport. Maximum inhibition was 49% at 2 mM Ca2+( P < 0.05). Fura 2 imaging confirmed that addition of 2 mM Ca2+produced a transient increase in intracellular Ca2+that preceded transport inhibition. Acute inhibition of Na+-GABA cotransport was reproduced by addition of thapsigargin (5 μM) and ionomycin (10 μM). Amino acid transport system A, assayed as a control, was not inhibited. Brief treatment with phorbol esters reproduced the specific inhibition of Na+-GABA cotransport, and the inhibition was blocked by staurosporine. Surface biotinylation confirmed that the response to phorbol esters was accompanied by loss of BGT1 protein from the plasma membrane, and immunohistochemistry showed a shift to an intracellular distribution. We conclude that BGT1 can be inhibited acutely by extracellular Ca2+through a mechanism involving BGT1 protein internalization, and protein kinase C may play a role.
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Affiliation(s)
- Stephen A Kempson
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
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35
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Zhou X, Ferraris JD, Burg MB. Mitochondrial reactive oxygen species contribute to high NaCl-induced activation of the transcription factor TonEBP/OREBP. Am J Physiol Renal Physiol 2005; 290:F1169-76. [PMID: 16303854 DOI: 10.1152/ajprenal.00378.2005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hypertonicity activates the transcription factor tonicity-responsive enhancer/osmotic response element binding protein (TonEBP/OREBP), resulting in increased expression of genes involved in osmoprotective accumulation of organic osmolytes, including glycine betaine, and in increased expression of osmoprotective heat shock proteins. Our previous studies showed that high NaCl increases reactive oxygen species (ROS), which contribute to activation of TonEBP/OREBP. Mitochondria are a major source of ROS. The purpose of the present study was to examine whether mitochondria produce the ROS that contribute to activation of TonEBP/OREBP. We inhibited mitochondrial ROS production in HEK293 cells with rotenone and myxothiazol, which inhibit mitochondrial complexes I and III, respectively. Rotenone (250 nM) and myxothiazol (12 nM) reduce high NaCl-induced ROS over 40%, whereas apocynin (100 microM), an inhibitor of NADPH oxidase, and allopurinol (100 microM), an inhibitor of xanthine oxidase, have no significant effect. Rotenone and myxothiazol reduce high NaCl-induced increases in TonEBP/OREBP transcriptional activity (ORE/TonE reporter assay) and BGT1 (betaine transporter) mRNA abundance ranging from 53 to 69%. They inhibit high NaCl-induced TonEBP/OREBP transactivating activity, but not its nuclear translocation. Release of ATP into the medium on hypertonic stress has been proposed to be a signal that triggers cellular osmotic responses. However, we do not detect release of ATP into the medium or inhibition of high NaCl-induced ORE/TonE reporter activity by an ATPase, apyrase (20 U/ml), indicating that high NaCl-induced activation of TonEBP/OREBP is not mediated by release of ATP. We conclude that high NaCl increases mitochondrial ROS production, which contributes to the activation of TonEBP/OREBP by increasing its transactivating activity.
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Affiliation(s)
- Xiaoming Zhou
- Div. of Nephrology, Uniformed Services Univ. of the Health Sciences, Bethesda, MD 20814, USA.
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36
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Nakashima E, Pop-Busui R, Towns R, Thomas TP, Hosaka Y, Nakamura J, Greene DA, Killen PD, Schroeder J, Larkin DD, Ho YL, Stevens MJ. Regulation of the human taurine transporter by oxidative stress in retinal pigment epithelial cells stably transformed to overexpress aldose reductase. Antioxid Redox Signal 2005; 7:1530-42. [PMID: 16356117 DOI: 10.1089/ars.2005.7.1530] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In diabetes, overexpression of aldose reductase (AR) and consequent glucose-induced impairment of antioxidant defense systems may predispose to oxidative stress and the development of diabetic complications, but the mechanisms are poorly understood. Taurine (2-aminoethanesulfonic acid) functions as an antioxidant, osmolyte, and calcium modulator such that its intracellular depletion could promote cytotoxicity in diabetes. The relationships of oxidative stress and basal AR gene expression to Na+-taurine cotransporter (TT) gene expression, protein abundance, and TT activity were therefore explored in low AR-expressing human retinal pigment epithelial (RPE) 47 cells and RPE 47 cells stably transformed to overexpress AR (RPE 75). Changes in TT gene expression were determined using a 4.6-kb TT promoter-luciferase fusion gene. Compared with RPE 47 cells, in high AR-expressing RPE 75 cells, TT promoter activity was decreased by 46%, which was prevented by an AR inhibitor. TT promoter activity increased up to 900% by prooxidant exposure, which was associated with increased TT peptide abundance and taurine transport. However, induction of TT promoter activity by oxidative stress was attenuated in high AR-expressing cells and partially corrected by AR inhibitor. Finally, exposure of RPE 75 cells to high glucose increased oxidative stress, but down-regulated TT expression. These studies demonstrate for the first time that the TT is regulated by oxidative stress and that overexpression of AR and high glucose impair this response. Abnormal expression of AR may therefore impair antioxidant defense, which may determine tissue susceptibility to chronic diabetic complications.
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Affiliation(s)
- Eitaro Nakashima
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
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37
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Yang T, Zhang A, Honeggar M, Kohan DE, Mizel D, Sanders K, Hoidal JR, Briggs JP, Schnermann JB. Hypertonic Induction of COX-2 in Collecting Duct Cells by Reactive Oxygen Species of Mitochondrial Origin. J Biol Chem 2005; 280:34966-73. [PMID: 16024921 DOI: 10.1074/jbc.m502430200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Our previous studies have documented MAPK mediation of the hypertonicity-induced stimulation of COX-2 expression in cultured renal medullary epithelial cells. The present study extends this observation by examining the role of reactive oxygen species (ROSs). ROS levels, determined using dichlorodihydrofluorescence diacetate and cytochrome c, were rapidly and significantly increased following exposure of mIMCD-K2 cells to media made hypertonic by adding NaCl. Hypertonic treatment (550 mosmol/kg) for 16 h induced a 5.6-fold increase in COX-2 protein levels and comparable increases in prostaglandin E(2) release, both of which were completely abolished by the NADPH oxidase inhibitor diphenyleneiodonium (25-50 microM). The general antioxidant N-acetyl-l-cysteine (6 mM), and the superoxide dismutase mimetic TEMPO (2.0 mm) reduced COX-2 levels by 75.6 and 79.8%, respectively. Exposure of mIMCD-K2 cells to exogenous O(2)(-.) generated by the xanthine/xanthine oxidase system mimicked the effect of hypertonicity on COX-2 expression and prostaglandin E(2) release. The increases in phosphorylation of ERK1/2 and p38 were detected 20 min following the hypertonic treatment and were both prevented by N-acetyl-l-cysteine. The increases in ROSs in response to hypertonic treatment were completely blocked by any one of the mitochondrial inhibitors tested, such as rotenone, thenoyltrifluoroacetone, or carbonyl cyanide m-chlorophenylhydrazone, associated with remarkable inhibition of COX-2 expression. In contrast, the increases in ROSs were not significantly altered in IMCD cells deficient in either gp91(phox) or p47(phox), nor were the increases in COX-2 expression. We conclude that ROSs derived from mitochondria, but not NADPH oxidase, mediate the hypertonicity-induced phosphorylation of MAPK and the stimulation of COX-2 expression.
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Affiliation(s)
- Tianxin Yang
- Department of Internal Medicine, University of Utah and Veterans Affairs Medical Center, Salt Lake City, Utah 84148, USA.
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38
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Ho SN. Intracellular water homeostasis and the mammalian cellular osmotic stress response. J Cell Physiol 2005; 206:9-15. [PMID: 15965902 DOI: 10.1002/jcp.20445] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The cellular response to osmotic stress ensures that the concentration of water inside the cell is maintained within a range that is compatible with biologic function. Single cell organisms are particularly dependent on mechanisms that permit adaptation to osmotic stress because each individual cell is directly exposed to the external environment. Mammals, however, limit osmotic stress by establishing an internal aqueous environment in which intravascular water and electrolytes are subject to sensitive and dynamic, organism-based homeostatic regulation. Recent studies of NFAT5/TonEBP, an essential mammalian osmoregulatory transcription factor, demonstrate the unexpected yet critical significance of cell-based osmotic regulation in vivo. These results highlight the fundamental importance of maintaining intracellular water homeostasis in the face of varying cellular metabolic activity and distinct tissue microenvironments.
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Affiliation(s)
- Steffan N Ho
- Department of Pathology, University of California-San Diego, La Jolla, California 92093-0644, USA.
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Kempson SA, Beck JA, Lammers PE, Gens JS, Montrose MH. Membrane insertion of betaine/GABA transporter during hypertonic stress correlates with nuclear accumulation of TonEBP. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1712:71-80. [PMID: 15950596 DOI: 10.1016/j.bbamem.2005.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2005] [Revised: 03/15/2005] [Accepted: 03/17/2005] [Indexed: 10/25/2022]
Abstract
MDCK cells stably transfected with betaine/GABA transporter tagged with EGFP (EGFP-BGT) were used to study plasma membrane insertion of EGFP-BGT. Adaptive response to hypertonicity requires nuclear migration of TonEBP. Confocal microscopy showed that after 6 h hypertonicity, the nuclear/cytoplasmic ratio of TonEBP fluorescence was increased to 2.4 compared to 1.4 in isotonic controls (P<0.001). The ratio in hypertonic cells was reduced by the proteasome inhibitor MG-132 in a dose-dependent way. Inhibition was 50% at 3 microM. After 6 h, hypertonicity expressed EGFP-BGT was localized in the plasma membrane, but there was no change in total EGFP-BGT abundance compared to isotonic controls. In contrast, EGFP-BGT remained mostly intracellular when 3 microM MG-132 was included in the hypertonic medium. The transport function of EGFP-BGT was studied as Na(+)-dependent uptake of [(3)H]GABA. This was not changed by MG-132 in isotonic controls, but MG-132 produced dose-dependent inhibition of hypertonic upregulation of Na(+)/GABA cotransport. Inhibition was 80% at 3 muM MG-132. Transport likely reflects membrane insertion of EGFP-BGT and there was a positive correlation (P<0.05) between Na(+)/GABA cotransport and the N/C ratio of TonEBP. Results are consistent with a role for TonEBP-mediated transcription in synthesis of additional proteins required for membrane insertion of EGFP-BGT protein.
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Affiliation(s)
- Stephen A Kempson
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, 46202-5120, USA.
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Bidmon B, Endemann M, Arbeiter K, Ruffingshofer D, Regele H, Herkner K, Eickelberg O, Aufricht C. Overexpression of HSP-72 confers cytoprotection in experimental peritoneal dialysis. Kidney Int 2005; 66:2300-7. [PMID: 15569319 DOI: 10.1111/j.1523-1755.2004.66040.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Peritoneal dialysis is complicated by mesothelial cell injury due to low biocompatibility of peritoneal dialysis fluid (PDF). We have previously demonstrated that heat shock protein (HSP)-72 is potently up-regulated in response to PDF exposure of mesothelial cells in in vitro and in vivo models of peritoneal dialysis. The aim of this study was to evaluate potential cytoprotective effects of overexpression of HSP-72. METHODS Cytoprotection was assessed by comparing cellular viability between pretreated versus nonpretreated human mesothelial cells (Met 5a; ATCC, Manassas, VA, USA, and primary cell cultures) subjected to extended, usually lethal PDF exposure times (120 min, CAPD2; Fresenius, Bad Homburg, Germany). Pretreatment was performed with exposure to PDF (60 min, CAPD2; Fresenius) or heat (15 min, 41.5 degrees C), and by transient transfection with HSP-72. RESULTS When mesothelial cells were pretreated by nonlethal exposure to PDF or heat, HSP-72 was markedly up-regulated (>5-fold, P < 0.01). Pretreated human mesothelial cells were significantly protected against subsequent "lethal" exposures to PDF, as assessed by dye exclusion (>50% reduction, P < 0.05) and lactate dehydrogenase (LDH) release (>30% reduction, P < 0.05). Comparable cytoprotection (50% reduction by dye exclusion) was indicated by overexpression of HSP-72 in cultered human mesothelial cells (>5-fold) after transient transfection with HSP-72. This cytoprotection was confirmed at a cellular basis by double staining techniques with HSP-72 and ApopTag (apoptosis detection kit). CONCLUSION Our study therefore shows that the mesothelial stress response confers cytoprotection in experimental peritoneal dialysis, mediated by the induction of HSP-72, and that the stimulus of the pretreatment does not have to be identical to the subsequent injury. These data offer the basis for an attractive novel therapeutic approach against PDF toxicity.
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Affiliation(s)
- Bettina Bidmon
- Department of Pathology, Yale University, School of Medicine, New Haven Connecticut, USA
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41
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Kempson SA, Montrose MH. Osmotic regulation of renal betaine transport: transcription and beyond. Pflugers Arch 2005; 449:227-34. [PMID: 15452713 DOI: 10.1007/s00424-004-1338-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cells in the kidney inner medulla are routinely exposed to high extracellular osmolarity during normal operation of the urinary concentrating mechanism. One adaptation critical for survival in this environment is the intracellular accumulation of organic osmolytes to balance the osmotic stress. Betaine is an important osmolyte that is accumulated via the betaine/gamma-aminobutyric acid transporter (BGT1) in the basolateral plasma membrane of medullary epithelial cells. In response to hypertonic stress, there is transcriptional activation of the BGT1 gene, followed by trafficking and membrane insertion of BGT1 protein. Transcriptional activation, triggered by changes in ionic strength and water content, is an early response that is a key regulatory step and has been studied in detail. Recent studies suggest there are additional post-transcriptional regulatory steps in the pathway leading to upregulation of BGT1 transport, and that additional proteins are required for membrane insertion. Reversal of this adaptive process, upon removal of hypertonic stress, involves a rapid efflux of betaine through specific release pathways, a reduction in betaine influx, and a slower downregulation of BGT1 protein abundance. There is much more to be learned about many of these steps in BGT1 regulation.
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Affiliation(s)
- Stephen A Kempson
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Medical Sciences Bldg., Room 309, 635 Barnhill Drive, Indianapolis, IN 46202-5120, USA.
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Abstract
SRC family kinases are a group of nine cytoplasmic protein tyrosine kinases essential for many cell functions. Some appear to be ubiquitously expressed, whereas others are highly tissue specific. The ability of members of the SRC family to influence ion transport has been recognized for several years. Mounting evidence suggests a broad role for SRC family kinases in the cell response to both hypertonic and hypotonic stress, and in the ensuing regulatory volume increase or decrease. In addition, members of this tyrosine kinase family participate in the mechanotransduction that accompanies cell membrane deformation. Finally, at least one SRC family member operates in concert with the p38 MAPK to regulate tonicity-dependent gene transcription.
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Affiliation(s)
- David M Cohen
- Division of Nephrology, Mailcode PP262, Oregon Health and Science Univ. 3314 SW US Veterans Hospital Rd., Portland, OR 97239, USA.
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Zhou X, Ferraris JD, Cai Q, Agarwal A, Burg MB. Increased reactive oxygen species contribute to high NaCl-induced activation of the osmoregulatory transcription factor TonEBP/OREBP. Am J Physiol Renal Physiol 2005; 289:F377-85. [PMID: 15769933 DOI: 10.1152/ajprenal.00463.2004] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The signaling pathways leading to high NaCl-induced activation of the transcription factor tonicity-responsive enhancer binding protein/osmotic response element binding protein (TonEBP/OREBP) remain incompletely understood. High NaCl has been reported to produce oxidative stress. Reactive oxygen species (ROS), which are a component of oxidative stress, contribute to regulation of transcription factors. The present study was undertaken to test whether the high NaCl-induced increase in ROS contributes to tonicity-dependent activation of TonEBP/OREBP. Human embryonic kidney 293 cells were used as a model. We find that raising NaCl increases ROS, including superoxide. N-acetylcysteine (NAC), an antioxidant, and MnTBAP, an inhibitor of superoxide, reduce high NaCl-induced superoxide activity and suppress both high NaCl-induced increase in TonEBP/OREBP transcriptional activity and high NaCl-induced increase in expression of BGT1mRNA, a transcriptional target of TonEBP/OREBP. Catalase, which decomposes hydrogen peroxide, does not have these effects, whether applied exogenously or overexpressed within the cells. Furthermore, NAC and MnTBAP, but not catalase, blunt high NaCl-induced increase in TonEBP/OREBP transactivation. N(G)-monomethyl-l-arginine, a general inhibitor of nitric oxide synthase, has no significant effect on either high NaCl-induced increase in superoxide or TonEBP/OREBP transcriptional activity, suggesting that the effects of ROS do not involve nitric oxide. Ouabain, an inhibitor of Na-K-ATPase, attenuates high NaCl-induced superoxide activity and inhibits TonEBP/OREBP transcriptional activity. We conclude that the high NaCl-induced increase in ROS, including superoxide, contributes to activation of TonEBP/OREBP by increasing its transactivation.
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Affiliation(s)
- Xiaoming Zhou
- Division of Nephrology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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Dmitrieva NI, Burg MB. Hypertonic stress response. Mutat Res 2005; 569:65-74. [PMID: 15603752 DOI: 10.1016/j.mrfmmm.2004.06.053] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 05/21/2004] [Accepted: 06/14/2004] [Indexed: 05/01/2023]
Abstract
Mammalian renal inner medullary cells are normally exposed to extremely high NaCl concentrations. Remarkably, under these normal conditions, the high NaCl causes DNA damage and inhibits its repair, yet the cells survive and function both in cell culture and in vivo. The interstitial NaCl concentration in parts of a normal renal medulla can be 500 mM or more, depending on the species. Studies of how the cells survive and function despite this extreme stress have led to the discovery of protective adaptations, including accumulation of large amounts of organic osmolytes, which normalize cell volume and intracellular ionic strength, despite the hypertonicity of the high NaCl. Those adaptations, however, do not prevent DNA damage. High NaCl induces DNA breaks rapidly, and the DNA breaks persist even after the cells become adapted to the high NaCl. The adapted cells proliferate rapidly in cell culture and function adequately in vivo despite the DNA breaks. Both in cell culture and in vivo the breaks are rapidly repaired if the NaCl concentration is lowered. Although acute elevation of NaCl causes transient cell cycle arrest and, when the elevation is too extreme, apoptosis, proliferation of adapted cells is not arrested in culture and apoptosis is not evident either in culture or in vivo. Further, high NaCl impairs activation of several components of the classical DNA damage response such as Mre11, H2AX and Chk1 leading to inhibition of DNA repair. Nevertheless, other regular participants in the DNA damage response, such as Gadd45a, Gadd153, p53, Hsp70, and ATM are still upregulated by high NaCl. How high NaCl causes the DNA breaks and how the cells survive them is conjectural at this point. We discuss possible answers to these questions, based on current knowledge about induction and processing of DNA breaks.
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Affiliation(s)
- Natalia I Dmitrieva
- Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung and Blood Institute, National Institutes of Health, Department of Health and Human Services, 10 Center Drive, Building 10, Room 6N260, Bethesda, MD 20892-1603, USA
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Xu H, Tian W, Lindsley JN, Oyama TT, Capasso JM, Rivard CJ, Cohen HT, Bagnasco SM, Anderson S, Cohen DM. EphA2: expression in the renal medulla and regulation by hypertonicity and urea stress in vitro and in vivo. Am J Physiol Renal Physiol 2004; 288:F855-66. [PMID: 15561974 DOI: 10.1152/ajprenal.00347.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
EphA2, a member of the large family of Eph receptor tyrosine kinases, is highly expressed in epithelial tissue and has been implicated in cell-cell and cell-matrix interactions, as well as cell growth and survival. Expression of EphA2 mRNA and protein was markedly upregulated by both hypertonic stress and by elevated urea concentrations in cells derived from the murine inner medullary collecting duct. This upregulation likely required transactivation of the epidermal growth factor (EGF) receptor tyrosine kinase and metalloproteinase-dependent ectodomain cleavage of an EGF receptor ligand, based on pharmacological inhibitor studies. A human EphA2 promoter fragment spanning nucleotides -4030 to +21 relative to the putative EphA2 transcriptional start site was responsive to tonicity but insensitive to urea. A promoter fragment spanning -1890 to +128 recapitulated both tonicity- and urea-dependent upregulation of expression, consistent with transcriptional activation. Neither the bona fide p53 response element at approximately -1.5 kb nor a pair of putative TonE elements at approximately -3 kb conferred the tonicity responsiveness. EphA2 mRNA and protein were expressed at low levels in rat renal cortex but at high levels in the collecting ducts of the renal medulla and papilla. Water deprivation in rats increased EphA2 expression in renal papilla, whereas dietary supplementation with 20% urea increased EphA2 expression in outer medulla. These data indicate that transcription and expression of the EphA2 receptor tyrosine kinase are regulated by tonicity and urea in vitro and suggest that this phenomenon is also operative in vivo. Renal medullary EphA2 expression may represent an adaptive response to medullary hypertonicity or urea exposure.
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Affiliation(s)
- Hongshi Xu
- Mailcode PP262, Oregon Health & Science Univ., 3314 S.W. US Veterans Hospital Rd., Portland, OR 97201, USA
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Pineda M, Font M, Bassi MT, Manzoni M, Borsani G, Marigo V, Fernández E, Río RMD, Purroy J, Zorzano A, Nunes V, Palacín M. The amino acid transporter asc-1 is not involved in cystinuria. Kidney Int 2004; 66:1453-64. [PMID: 15458438 DOI: 10.1111/j.1523-1755.2004.00908.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The human amino acid transporter asc-1 (SLC7A10) exhibits substrate selectivity for small neutral amino acids, including cysteine, is expressed in kidney, is located close to the cystinuria B gene and presents sequence variants (e.g., E112D) in some cystinuria patients. We have cloned human asc-1, assessed its transport characteristics, localized its expression in kidney, searched for mutations in cystinuria patients, and tested the transport function of variant E112D. METHODS We used an EST-based homology cloning strategy. Transport characteristics of asc-1 were assessed by coexpression with 4F2hc in Xenopus oocytes and HeLa cells. Localization of asc-1 mRNA in kidney was assessed by in situ hybridization. Exons and intron-exon boundaries were polymerase chain reaction (PCR)-amplified from blood cell DNA and mutational screening was performed by single-stranded conformational polymorphism (SSCP). RESULTS Asc-1 reaches the plasma membrane in HeLa cells, unlike in oocytes, most probably by interaction with endogenous 4F2hc and presents similar transport characteristics to those in oocytes coexpressing asc-1/4F2hc. Asc-1 mediates a substantial efflux of alanine in a facilitated diffusion mode of transport. Expression of asc-1 mRNA localized to Henle's loop, distal tubules, and collecting ducts. Finally, SLC7A10 polymorphisms were identified in cystinuria probands and the SLC7A10 sequence variant E112D showed full transport activity. CONCLUSION The lack of expression of asc-1 in the proximal tubule indicates that it plays no role in the bulk of renal reabsorption of amino acids. No mutations causing cystinuria have been found in SLC7A10. The facilitated diffusion mode of transport and the expression in distal nephron suggest a role for asc-1 in osmotic adaptation.
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Affiliation(s)
- Marta Pineda
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Spain
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Wright EM, Turk E. The sodium/glucose cotransport family SLC5. Pflugers Arch 2004; 447:510-8. [PMID: 12748858 DOI: 10.1007/s00424-003-1063-6] [Citation(s) in RCA: 201] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2003] [Accepted: 03/28/2003] [Indexed: 01/10/2023]
Abstract
The sodium/glucose cotransporter family (SLCA5) has 220 or more members in animal and bacterial cells. There are 11 human genes expressed in tissues ranging from epithelia to the central nervous system. The functions of nine have been revealed by studies using heterologous expression systems: six are tightly coupled plasma membrane Na(+)/substrate cotransporters for solutes such as glucose, myo-inositol and iodide; one is a Na(+)/Cl(-)/choline cotransporter; one is an anion transporter; and another is a glucose-activated ion channel. The exon organization of eight genes is similar in that each comprises 14-15 exons. The choline transporter (CHT) is encoded in eight exons and the Na(+)-dependent myo-inositol transporter (SMIT) in one exon. Mutations in three genes produce genetic diseases (glucose-galactose malabsorption, renal glycosuria and hypothyroidism). Members of this family are multifunctional membrane proteins in that they also behave as uniporters, urea and water channels, and urea and water cotransporters. Consequently it is a challenge to determine the role(s) of these genes in human physiology and pathology.
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Affiliation(s)
- Ernest M Wright
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1751, USA.
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Cai Q, Ferraris JD, Burg MB. Greater tolerance of renal medullary cells for a slow increase in osmolality is associated with enhanced expression of HSP70 and other osmoprotective genes. Am J Physiol Renal Physiol 2004; 286:F58-67. [PMID: 13129850 DOI: 10.1152/ajprenal.00037.2003] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In tests of osmotic tolerance of renal inner medullary cells in tissue culture, osmolality has usually been increased in a single step, whereas in vivo the increase occurs gradually over several hours. We previously found that more passage 2 mouse inner medullary epithelial (p2mIME) cells survive a linear increase in NaCl and urea from 640 to 1,640 mosmol/kgH2O over 20 h (which is similar to the change that may occur in vivo) than they do a step increase. The present studies examine accompanying differences in gene expression. Among mRNAs of genes known to be protective, tonicity-responsive enhancer binding protein and aldose reductase increase with a linear but decrease with a step increase; betaine transporter BGT1 decreases with a step but not a linear increase; heat shock protein 70.1 (HSP70.1) and HSP70.3 increase more with a linear than a step increase; and osmotic stress protein 94 and heme oxygenase-1 increase with a linear but decrease with a step increase. mRNAs for known urea-responsive proteins, GADD153 and Egr-1, increase with both a step and linear increase. A step increase in urea alone reduces mRNAs, similar to the combination of NaCl and urea, but a step increase in NaCl alone does not. HSP70 protein increases substantially with a linear rise in osmolality but does not change significantly with a step rise. We speculate that poorer survival of p2mIME cells with a step than with linear increase in NaCl and urea is accounted for, at least in part, by urea-induced suppression of protective genes, particularly HSP70.
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Affiliation(s)
- Qi Cai
- National Heart, Lung and Blood Institute, National Institutes of Health, Bldg. 10, Rm. 6N319, Bethesda, MD 20892-1603, USA.
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Zhao H, Tian W, Tai C, Cohen DM. Hypertonic induction of COX-2 expression in renal medullary epithelial cells requires transactivation of the EGFR. Am J Physiol Renal Physiol 2003; 285:F281-8. [PMID: 12670830 DOI: 10.1152/ajprenal.00030.2003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Hypertonic stress increases expression of cyclooxygenase-2 (COX-2) in renal medullary epithelial and interstitial cells. Because hypertonic COX-2 expression is, in part, sensitive to inhibition of the ERK MAPK, an effector of activated receptor tyrosine kinases such as the EGF receptor, we investigated a role for this receptor in signaling to COX-2 expression. Hypertonic stress increased COX-2 expression at the mRNA and protein levels at 6 and 24 h of hypertonic treatment. Two potent, specific inhibitors of the EGF receptor kinase, AG-1478 and PD-153035, abrogated this effect. These inhibitors also blocked the ability of hypertonic stress to increase PGE2 release; in addition, they partially blocked tonicity-dependent phosphorylation of ERK but not of the related MAPKs, JNK or p38. Pharmacological inhibition of ERK activation partially blocked tonicity-dependent COX-2 expression. Hypertonic induction of COX-2 was likely transcriptionally mediated, as NaCl stress increased luciferase reporter gene activity under control of the human COX-2 promoter, and this effect was also sensitive to inhibition of the EGF receptor kinase. Metalloproteinase action is required for transactivation of the EGF receptor. Pharmacological inhibition of metalloproteinase function blocked tonicity-inducible COX-2 expression. Furthermore, the effect of hypertonicity on COX-2 expression was also evident in the EGF-responsive Madin-Darby canine kidney and 3T3 cell lines but was virtually absent from the EGF-unresponsive (and EGF receptor null) Chinese hamster-derived CHO cell line. Taken together, these data indicate that hypertonicity-dependent COX-2 expression in medullary epithelial cells requires transactivation of the EGF receptor and, potentially, ectodomain cleavage of an EGF receptor ligand.
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Affiliation(s)
- Hongyu Zhao
- Division of Nephrology and Hypertension, Oregon Health and Science University and the Portland Veterans Affairs Medical Center, Portland, OR 97201, USA
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Abstract
NFAT5/TonEBP, the most recently described member of the rel/NFkappaB/NFAT family of signal-dependent transcription factors, is activated by extracellular hypertonicity-a cellular stress of particular and perhaps unique physiologic relevance to cells of the renal medulla. Accumulating evidence suggests that NFAT5/TonEBP also functions in vivo under isotonic conditions as part of a ubiquitous regulatory mechanism that senses and adjusts available intracellular volume during cell growth to establish an intracellular environment appropriate for optimal cell proliferation.
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Affiliation(s)
- Steffan N Ho
- Department of Pathology, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0644, USA.
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